Insulating circuit substrate and method for producing insulating circuit substrate

Abstract

An insulating circuit substrate includes an insulating layer; and a circuit layer formed on one surface of the insulating layer, in which the insulating layer has a core layer formed of an epoxy resin containing an inorganic filler, and a skin layer formed on the circuit layer side of the core layer and formed of a polyimide resin containing an inorganic filler, an amount of the inorganic filler in the epoxy resin forming the core layer is in a range of 80 vol % or more and 95 vol % or less, and an amount of the inorganic filler in the polyimide resin forming the skin layer is in a range of 10 vol % or more and 30 vol % or less.

What is claimed is: 
     
       1. An insulating circuit substrate comprising:
 an insulating layer; and 
 a circuit layer formed on one surface of the insulating layer, 
 wherein the insulating layer has a core layer formed of an epoxy resin containing an inorganic filler, and a skin layer formed of a polyimide resin containing an inorganic filler and formed on the circuit layer side of the core layer, 
 the inorganic filler in the epoxy resin is made of Al 2 O 3 , BN or AlN, or a mixture thereof, 
 an amount of the inorganic filler in the epoxy resin forming the core layer is in a range of 80 vol % or more and 95 vol % or less, 
 an amount of the inorganic filler in the polyimide resin forming the skin layer is in a range of 10 vol % or more and 30 vol % or less, 
 a ratio of the thickness of the skin layer to a thickness of the core layer is 0.020 to 0.071, and 
 a thickness of the skin layer is 3 μm to 5 μm. 
 
     
     
       2. The insulating circuit substrate according to  claim 1 ,
 wherein a metal layer is formed on a surface of the insulating layer on an opposite side to the circuit layer, and a skin layer formed of a polyimide resin is formed on the metal layer side of the core layer. 
 
     
     
       3. A method for manufacturing an insulating circuit substrate by which the insulating circuit substrate according to  claim 1  is manufactured, the method comprising:
 a core layer forming step of forming a core layer by curing an epoxy resin composition including an inorganic filler and an epoxy resin; 
 a polyimide resin composition providing step of providing a polyimide resin composition including an inorganic filler and a polyimide resin on a surface of the core layer; 
 a metal plate laminating step of laminating a metal plate to be a circuit layer on the polyimide resin composition; and 
 a thermocompression bonding step of pressing and heating the metal plate, the polyimide resin composition, and the core layer in a laminating direction, curing the polyimide resin composition to form a skin layer, and bonding the metal plate and the insulating layer to form the circuit layer. 
 
     
     
       4. A method for manufacturing an insulating circuit substrate by which the insulating circuit substrate according to  claim 1  is manufactured, the method comprising:
 a polyimide resin composition providing step of providing a polyimide resin composition including an inorganic filler and the polyimide resin, on a metal plate to be the circuit layer; 
 an epoxy resin composition laminating step of laminating an epoxy resin composition including an inorganic filler and an epoxy resin on the polyimide resin composition; and 
 a thermocompression bonding step of pressing and heating the metal plate, the polyimide resin composition, and the epoxy resin composition in a laminating direction, curing the polyimide resin composition to form a skin layer, curing the epoxy resin composition to form the core layer, and bonding the metal plate and the insulating layer to form the circuit layer. 
 
     
     
       5. The insulating circuit substrate according to  claim 1 , wherein the inorganic filler in the polyamide resin is made of Al 2 O 3 , BN or AlN, or a mixture thereof. 
     
     
       6. The insulating circuit substrate according to  claim 1 , wherein a lower limit of the amount of inorganic filler in the epoxy resin is 85 vol %. 
     
     
       7. The insulating circuit substrate according to  claim 1 , wherein a lower limit of the amount of inorganic filler in the epoxy resin is 90 vol %. 
     
     
       8. The insulating circuit substrate according to  claim 1 , wherein an upper limit of the amount of inorganic filler in the polyimide resin is 25 vol %. 
     
     
       9. A method for manufacturing an insulating circuit substrate by which the insulating circuit substrate according to  claim 2  is manufactured, the method comprising:
 a core layer forming step of forming a core layer by curing an epoxy resin composition including an inorganic filler and an epoxy resin; 
 a polyimide resin composition providing step of providing a polyimide resin composition including an inorganic filler and a polyimide resin on a surface of the core layer; 
 a metal plate laminating step of laminating a metal plate to be a circuit layer on the polyimide resin composition; and 
 a thermocompression bonding step of pressing and heating the metal plate, the polyimide resin composition, and the core layer in a laminating direction, curing the polyimide resin composition to form a skin layer, and bonding the metal plate and the insulating layer to form the circuit layer. 
 
     
     
       10. A method for manufacturing an insulating circuit substrate by which the insulating circuit substrate according to  claim 2  is manufactured, the method comprising:
 a polyimide resin composition providing step of providing a polyimide resin composition including an inorganic filler and the polyimide resin, on a metal plate to be the circuit layer; 
 an epoxy resin composition laminating step of laminating an epoxy resin composition including an inorganic filler and an epoxy resin on the polyimide resin composition; and 
 a thermocompression bonding step of pressing and heating the metal plate, the polyimide resin composition, and the epoxy resin composition in a laminating direction, curing the polyimide resin composition to form a skin layer, curing the epoxy resin composition to form the core layer, and bonding the metal plate and the insulating layer to form the circuit layer. 
 
     
     
       11. The method for manufacturing an insulating circuit substrate according to  claim 3 , further comprising:
 a circuit pattern forming step of forming a circuit pattern by etching the metal plate to be the circuit layer after the thermocompression bonding step. 
 
     
     
       12. The method for manufacturing an insulating circuit substrate according to  claim 3 ,
 wherein a plurality of metal pieces provided in a circuit pattern are used as the metal plate and, in the thermocompression bonding step, a pressing member is disposed in a region, in which the metal pieces are not provided, and pressed. 
 
     
     
       13. The method for manufacturing an insulating circuit substrate according to  claim 4 , further comprising:
 a circuit pattern forming step of forming a circuit pattern by etching the metal plate to be the circuit layer after the thermocompression bonding step. 
 
     
     
       14. The method for manufacturing an insulating circuit substrate according to  claim 4 ,
 wherein a plurality of metal pieces provided in a circuit pattern are used as the metal plate and, in the thermocompression bonding step, a pressing member is disposed in a region, in which the metal pieces are not provided, and pressed. 
 
     
     
       15. The method for manufacturing an insulating circuit substrate according to  claim 9 , further comprising:
 a circuit pattern forming step of forming a circuit pattern by etching the metal plate to be the circuit layer after the thermocompression bonding step. 
 
     
     
       16. The method for manufacturing an insulating circuit substrate according to  claim 9 ,
 wherein a plurality of metal pieces provided in a circuit pattern are used as the metal plate and, in the thermocompression bonding step, a pressing member is disposed in a region, in which the metal pieces are not provided, and pressed. 
 
     
     
       17. The method for manufacturing an insulating circuit substrate according to  claim 10 , further comprising:
 a circuit pattern forming step of forming a circuit pattern by etching the metal plate to be the circuit layer after the thermocompression bonding step. 
 
     
     
       18. The method for manufacturing an insulating circuit substrate according to  claim 10 ,
 wherein a plurality of metal pieces provided in a circuit pattern are used as the metal plate and, in the thermocompression bonding step, a pressing member is disposed in a region, in which the metal pieces are not provided, and pressed. 
 
     
     
       19. An insulating circuit substrate for a power module, an LED module or a thermoelectric module, the insulating circuit substrate comprising:
 an insulating layer; 
 a circuit layer formed on one surface of the insulating layer; and 
 a heat sink, 
 wherein the insulating layer has a core layer formed of an epoxy resin containing an inorganic filler, and a first skin layer formed of a polyimide resin containing an inorganic filler and formed on the circuit layer side of the core layer, 
 the inorganic filler in the epoxy resin is made of Al 2 O 3 , BN or AlN, or a mixture thereof, 
 an amount of the inorganic filler in the epoxy resin forming the core layer is in a range of 80 vol % or more and 95 vol % or less, 
 the circuit layer is configured for a power semiconductor element, an LED element or a thermoelectric element to be mounted on, 
 a metal layer is formed on a surface of the insulating layer on an opposite side to the circuit layer, and a second skin layer formed of a polyimide resin is formed on the metal layer side of the core layer, 
 the heat sink is bonded to the metal layer, 
 amounts of the inorganic filler in the polyimide resin forming the first and second skin layers are in a range of 10 vol % or more and 30 vol % or less, 
 thicknesses of the first and second skin layers are 3 μm to 5 μm, 
 a ratio of the thickness of the first skin layer to a thickness of the core layer is 0.020 to 0.071 and a ratio of the thickness of the second skin layer to a thickness of the core layer is 0.020 to 0.071, 
 a thickness of the circuit layer is in a range of 0.3 mm or more and 3 mm or less, and 
 the insulating circuit substrate is manufactured by thermo-compressing: metal pieces to be the circuit layer; a polyimide resin composition to be the first skin layer; the core layer; a polyimide resin composition to be the second skin layer; and a metal layer plate to be the metal layer, in an order, and by bonding the heat sink to the metal layer after thermo-compressing.